Controlling spray drift of pesticides with self-emulsifiable esters

ABSTRACT

Spray drift during the application of agricultural chemicals is reduced by incorporating a self-emulsifiable ester into the liquid to be sprayed.

This application claims the benefit of U.S. Provisional Application Ser.No. 61/110,060 filed on Oct. 31, 2008.

BACKGROUND OF THE INVENTION

The present invention concerns a novel method to reduce spray driftduring the application of agricultural chemicals by incorporating aself-emulsifiable ester into the liquid to be sprayed. Agriculturalspraying by economical and available technologies uses hydraulic spraynozzles that inherently produce a wide spectrum of spray droplet sizes.The potential for these spray droplets to drift from the initial,desired site of application is found to be a function of droplet size,with smaller droplets having a higher propensity for off-targetmovement. Significant research efforts, involving numerous field trials,wind tunnel tests and subsequent generation of predictive math modelshave led to a greatly enhanced understanding of the relationship betweenspray droplet size and potential for off-target drift. Although otherfactors such as meteorological conditions and spray boom heightcontribute to the potential for drift, spray droplet size distributionhas been found to be a predominant factor. Teske et. al. (Teske M. E.,Hewitt A. J., Valcore, D. L. 2004.The Role of Small Droplets inClassifying Drop Size Distributions ILASS Americas 17^(th) AnnualConference: Arlington, Va.) have reported a value of <156 microns (μ) asthe fraction of the spray droplet distribution that contributes todrift. Wolf (www.bae.ksu.edu/faculty/wolf/drift.htm) cites a value of<200μ as the driftable fraction. A good estimation of droplet sizelikely to contribute to drift, therefore, is the fraction below about175μ.

The negative consequences of off-target movement can be quitepronounced. Some herbicides have demonstrated very sensitivephytotoxicity to particular plant species at extremely low parts permillion (ppm) or even parts per billion (ppb) levels, resulting inrestricted applications around sensitive crops, orchards and residentialplantings. For example, the California Dept of Pesticide Regulationimposes buffers of ½-2 miles (0.8-3.2 kilometers) for propanilcontaining herbicides applied aerially in the San Joaquin valley.

High molecular weight, water-soluble polymers are currently added tospray compositions as a tank mix to increase droplet size and therebyreduce drift (see, for example, WO 2008/101818 A2 and U.S. Pat. No.6,214,771 B1). However, high molecular weight, water-soluble polymersare not entirely satisfactory because they are expensive to use at theconcentrations required to substantially increase droplet size.Furthermore, research has shown that many commercially available driftretardants typically do not work with many aerially applied herbicidetank mixtures, due to pump shear, wind shear and other performanceissues, which are more pronounced in high speed aerial applicationconditions. See Hewitt, A. J. (2003) Drift Control Adjuvants in SprayApplications: Performance and Regulatory Aspects. Proc. Third LatinAmerican Symposium on Agricultural Adjuvants, Sao Paulo, Brazil.

SUMMARY OF THE INVENTION

It has now been found that by incorporating a self-emulsifiable esterinto an agricultural spray mixture that spray drift during applicationcan be reduced. The present invention concerns a method to reduce spraydrift during the application of a pesticide which comprisesincorporating into the pesticidal spray from about 0.01 to about 5percent vol/vol of a self-emulsifiable ester or mixture thereof. Thereduction in spray drift may result from a variety of factors includinga reduction in the production of fine spray droplets (<175μ in diameter)and an increase in the volume median diameter (VMD) of the spraydroplets. For a given spray apparatus, application, and condition, andbased on the self-emulsifiable ester, the median diameter of theplurality of spray droplets is increased above that of a spraycomposition without said self-emulsifiable ester.

Another embodiment of the invention is a premix formulation whichcomprises from about 1 to about 90 weight percent of a pesticide, andfrom about 0.05 to about 30 weight percent of a self-emulsifiable ester.The premix formulation is preferably a solution, emulsion, suspension,wettable or soluble powder, or water-dispersible or water-solublegranule formulation.

DETAILED DESCRIPTION OF THE INVENTION

The method to reduce spray drift applies to the application of anypesticide or crop protection agent including herbicides, fungicides andinsecticides. Particularly preferred herbicides to which this methodapplies include cyhalofop-butyl, haloxyfop, penoxsulam, flumetsulam,cloransulam-methyl, florasulam, pyroxsulam, diclosulam, fluroxypyr,clopyralid, acetochlor, triclopyr, isoxaben, 2,4-D, MCPA, dicamba, MSMA,oxyfluorfen, oryzalin, trifluralin, benfluralin, ethalfluralin,aminopyralid, atrazine, picloram, tebuthiuron, pendimethalin, propanil,propyzamide, glyphosate and glufosinate. Particularly preferredinsecticides to which this method applies include organophosphates suchas chlorpyrifos, MAC's such as halofenozide, methoxyfenozide andtebufenozide, pyrethroids such as gamma-cyhalothrin and deltamethrin,and biopesticides such as spinosad and spinetoram. Particularlypreferred fungicides to which this method applies include mancozeb,myclobutanil, fenbuconazole, zoxamide, propiconazole, quinoxyfen andthifluzamide. The present invention is particularly useful for theapplication of herbicides, most particularly with herbicides that aresubject to restricted applications around sensitive crops which have notbeen modified to be tolerant of them, such as 2,4-D, dicamba, glyphosateand glufosinate.

Self-emulsifiable esters (SEEs) used in the present invention arecharacterized as molecules that combine oil (hydrophobic), hydrophilicnonionic, and, optionally, anionic functionality in a single moleculethat can form uniform stable emulsions in an aqueous phase. Contrary toconventional emulsions in which one or more oils would be blended withone or more surfactants (emulsifiers), no such additives are necessaryfor the emulsion disclosed in the present invention. Uniform, stableaqueous emulsions can be formed with these SEEs without the use ofadditional emulsifiers or oils by little to moderate agitation of theSEE and water mixture. Examples of these SEEs include, but are notlimited to, the following: (1) trimer acid based self-emulsifiableesters produced by the polymerization of oleic and linoleic acids havinga C₅₄ lipophilic backbone and an ester portion of the moleculecontaining both nonionic and anionic surfactant functionality (see, forexample, U.S. Pat. Nos. 5,688,750 and 5,707,945; commercially availableunder the trademark Priolube products from Croda Uniqema, Inc); (2)esters prepared by esterification of ethoxylated trimethylolpropane byfatty acids and dicarboxylic acid anhydrides (see, for example,WO1990/005714); (3) esters derived from high molecular weight dibasicacids, polyoxyalkylene glycols and monofunctional aliphatic alcohols(see, for example, U.S. Pat. No. 3,912,642); (4) self emulsifying estercompounds prepared by reacting an ethoxylated trimethylol propane with acarboxylic acid or a reactive derivative thereof, such as an anhydride,as disclosed in U.S. Pat. No. 5,219,479; (5) succinate triglyceride oilderived from maleating triglyceride oil from a plant or land animal(see, for example, WO 2005/071050 A1) commercially available as thetrademark VEG-ESTER products of Lubrizol, Inc.; (6) ethoxylated fattyacid esters (see, for example, WO 1996/022109); (7) alkoxylate estersprepared by reacting an alcohol with ethylene oxide and propylene oxideand/or butylene oxide and capping the resulting alkoxylate with analkanoic or aromatic acid as disclosed in U.S. Pat. No. 4,559,226,available commercially as the trademark Hetester products from theBernet Chemical Company, Inc., a division of Alzo International, Inc.;and (8) alkoxylated triglycerides commercially available as thetrademark Aqnique RSO and Agnique SBO products from Cognis, Inc.

The self-emulsifiable esters can be incorporated into the pesticidalspray by being tank-mixed directly with the diluted pesticidalformulation or by being provided as a pre-mix with the pesticidalformulation prior to dilution to the final spray volume. Theself-emulsifiable ester is incorporated at a concentration from about0.01 to about 5 volume percent of the final spray volume, preferablyfrom about 0.05 to about 1.0 volume percent of the final spray volume,and most preferably from about 0.05 to about 0.2 volume percent of thefinal spray volume.

The present method reduces off-target movement of the pesticide spray inboth aerial and ground applications.

The optimum droplet size depends on the application for which thecomposition is used. If droplets are too large, there will be lesscoverage by the spray; i.e, large droplets will land in certain areaswhile areas in between will receive little or no spray composition. Themaximum acceptable droplet size may depend on the amount of compositionbeing applied per unit area and the need for uniformity in spraycoverage. Smaller droplets provide more even coverage, but are moreprone to drift during spraying. If it is particularly windy duringspraying, larger droplets may be preferred, whereas on a calmer daysmaller droplets may be preferred.

The spray droplet size may also depend on the spray apparatus; e.g.,nozzle size and configuration. One skilled in the art will readily beable to adjust the percentage of surfactant and/or polymer in thecomposition to provide the desired droplet size for a given apparatus,application, and condition. In any event, for a given spray apparatus,application, and condition, and based on the self-emulsifiable ester,the median diameter of the plurality of spray droplets is increasedabove that of a spray composition without said self-emulsifiable ester.

In addition to the method set forth above, the present invention alsoembraces premix formulations comprising from about 1 to about 90 weightpercent, preferably from about 5 to about 70 weight percent, and mostpreferably from about 20 to about 60 weight percent of a pesticide andfrom about 0.05 to about 30 weight percent, preferably from about 1.0 toabout 20 weight percent, and most preferably from about 1.0 to about 10weight percent of a self-emulsifiable ester.

Optionally, the composition of the present invention may contain asurfactant. The surfactants can be anionic, cationic or nonionic incharacter. Typical surfactants include salts of alkyl sulfates, such asdiethanolammonium lauryl sulfate; alkylarylsulfonate salts, such ascalcium dodecylbenzenesulfonate; alkyl and/or arylalkylphenol-alkyleneoxide addition products, such as nonylphenol-C₁₈ ethoxylate;alcohol-alkylene oxide addition products, such as tridecyl alcohol-C₁₆ethoxylate; soaps, such as sodium stearate; alkylnaphthalenesulfonatesalts, such as sodium dibutylnaphthalenesulfonate; dialkyl esters ofsulfosuccinate salts, such as sodium di(2-ethylhexyl)sulfosuccinate;sorbitol esters, such as sorbitol oleate; quaternary amines, such aslauryl trimethylammonium chloride; ethoxylated amines, such astallowamine ethoxylated; betaine surfactants, such as cocoamidopropylbetaine; polyethylene glycol esters of fatty acids, such as polyethyleneglycol stearate; block copolymers of ethylene oxide and propylene oxide;salts of mono and dialkyl phosphate esters; and mixtures thereof. Thesurfactant or mixture of surfactants is usually present at aconcentration of from about 1 to about 20 weight percent of theformulation.

In addition to the formulations set forth above, the present inventionalso embraces formulations in combination with one or more additionalcompatible ingredients. Other additional ingredients may include, forexample, one or more other pesticides, dyes, and any other additionalingredients providing functional utility, such as, for example,stabilizers, fragrances, viscosity-lowering additives, and freeze-pointdepressants.

The premix formulation is preferably a solution, emulsion, suspension,wettable or soluble powder, or water-dispersible or water-solublegranule formulation.

The following Examples illustrate the invention.

Example 1

To make each concentrated 2,4-D formulations A to G as in Table 1, astainless steel beaker equipped with a mechanical stirrer was firstcharged with 90 grams DMA 6 SEQUESTERED, containing 68.8% 2,4-Ddimethylammonium salt in an aqueous solution. 10 grams total of thedifferent combinations of the Priolube products were then addedaccording to the compositions in Table 1. Each liquid mixture wasstirred to homogenize the composition and to furnish the formulation.

The aqueous spray solution was made by adding 1 mL of the eachformulation to 99 mL of deionized water to make a 1% v/v dilution. Thespray solution was then sprayed through a TeeJet 8002 flat fan nozzle at40 psi (276 kilopascal (kPa)) and the droplet size was measured by usinga Sympatec Helos particle sizer. The measurements were made with the tipof the nozzle at either 6 or 12 inches (15.24 or 30.48 centimeters (cm))from the measurement zone of the particle sizer. The results arereported in Table 2 (6 inches; 15.24 cm) and Table 3 (12 inches; 30.48cm). As can be seen from these results, the driftable fines with dropletsize less than 175 μm by the spray composition of the present inventionare largely reduced. The present invention efficiently reduces driftablefine droplets by narrowing the drop size distribution profile withoutsignificantly increasing the large droplets, thus with minimal effect onspray coverage and quality.

TABLE 1 Compositions for Formulations of Example 1. Priolube PriolubePriolube Formulation # DMA 6 SEQ*, g 3955, g 3952, g 3953, g DMA 6 SEQ*100 0 0 0 A 90 0 0 10 B 90 0 5 5 C 90 0 10 0 D 90 3.3 3.3 3.3 E 90 5 0 5F 90 5 5 0 G 90 10 0 0 *DMA 6 SEQUESTERED, a 6 lb (2.72 kilograms (kg))ae/gal 2,4-D-dimethylammonium Manufacturing Use Concentrate of DowAgroSciences, LLC.

TABLE 2 Spray Performance of Example 1 Compositions 6 Inches (15.24 cm)from Nozzle. Percent < Spray solution VMD*, μm 100** μm Percent < 175***μm DMA 6 SEQ 1% 213.00 15.99 38.72 A 1% 223.60 14.21 35.64 B 1% 287.444.36 16.24 C 1% 281.19 4.65 17.55 D 1% 278.43 5.27 18.76 E 1% 267.026.03 21.37 F 1% 255.07 8.52 25.99 G 1% 238.08 10.86 30.62 *VMD—volumemedian diameter **Percent of spray volume with droplet size less than100 μm ***Percent of spray volume with droplet size less than 175 μm

TABLE 3 Spray Performance of Example 1 Compositions 12 Inches (30.48 cm)from Nozzle. VMD *, Percent < Percent < Spray solution μm 100** μm175*** μm DMA 6 SEQ 1% 164 20.8 53.7 A 1% 204 13.7 40.6 B 1% 251 7.225.9 C 1% 248 7.9 27.6 D 1% 227 10.3 33.4 E 1% 237 9.0 30.5 F 1% 231 9.832.4 G 1% 190 15.4 44.8

Example 2

The spray solution of formulations of H to N at 1% v/v was madefollowing the same procedure as in Example 1. To each spray solution wasthen added the proper amount of glyphosate dimethylammonium salt toachieve an acid equivalent ratio between 2,4-D and glyphosate of 1:1.The dilution was stirred to homogenous to furnish the spray solution. Itwas then sprayed following the same procedure and settings as describedin Example 1. The results are shown in Table 4 (measured 6 inches (15.24cm) from spray nozzle) and Table 5 (measured 12 inches (30.48 cm) fromnozzle). As can be seen from these results, the addition of glyphosatedoes not significantly affect the spray distribution from previousexample, indicating the robustness of the present invention incontrolling the driftable fines.

TABLE 4 Spray Performance of Example 2 Compositions 6 Inches (15.24 cm)from Nozzle. Spray Percent < Percent < Spray solution Composition VMD,μm 100 μm 175 μm DMA 6 SEQ 1% 213.00 15.99 38.72 H A 1% + 240.35 10.0230.09 glyphosate I B 1% + 279.53 4.58 17.28 glyphosate J C 1% + 272.805.06 19.02 glyphosate K D 1% + 260.34 6.09 22.43 glyphosate L E 1% +257.79 6.54 23.32 glyphosate M F 1% + 254.81 7.06 24.41 glyphosate N G1% + 235.76 10.24 30.60 glyphosate

TABLE 5 Spray Performance of Example 2 Compositions 12 Inches (30.48 cm)from Nozzle. Spray Percent < Percent < Spray solution Composition VMD,μm 100 μm 175 μm DMA 6 SEQ 1% + 148 25.2 60.2 glyphosate 1% H A 1% + 18018.0 48.2 glyphosate I B 1% + 250 7.4 26.5 glyphosate J C 1% + 235 9.230.8 glyphosate K D 1% + 230 10.0 32.7 glyphosate L E 1% + 224 10.6 34.3glyphosate M F 1% + 230 9.7 32.4 glyphosate N G 1% + 207 12.9 39.6glyphosate

Example 3

To make each of the concentrated herbicide formulations O to Q shown in.Table 4, a stainless steel beaker equipped with a mechanical stirrer wasfirst charged with 95 g of the herbicide formulation (either DMA6 SEQ,Garlon 3A*, or Milestone**) and 5 g of Hetester PCA (obtained from AlzoInternational Inc.). Each liquid mixture was stirred to homogenize thecomposition and to furnish the formulation for subsequent dilution andspray analysis.

The aqueous spray solutions of each were made by adding 2 ml of each ofthe formulations to 98 ml of deionized water to make 2% v/v dilutions.The solutions were then sprayed following the same procedure andsettings as described in Example 1, with the spray nozzle 12 inches(30.48 cm) from particle sizer measurement zone. The results are shownin Table 6. As can be seen from these results, the present inventiondoes effectively reduce the driftable fine droplets by narrowing thedrop size distribution profile without significantly increasing thelarge droplets, thus having minimal effect on spray coverage andquality.

TABLE 6 Spray Performance of Example 3 Compositions. Spray Spray Percent< Solution Composition VMD, μm 100 μm Percent < 175 μm DMA6 163.15 21.854.2 SEQ 2% Garlon 181.20 17.9 47.8 3A 2% Milestone 152.11 24.9 58.5 2%O 2% DMA6 SEQ + 165.72 21.2 53.2 Hetester PCA P 2% Garlon 3A + 255.118.8 25.5 Hetester PCA Q 2% Milestone + 243.62 8.6 26.7 Hetester PCA*Garlon 3A, a 3 lb (1.36 kg) ae/gal triclopyr triethylamine saltcommercial product of Dow AgroSciences, LLC. **Milestone, a 2 lb (0.91kg) ae/gal aminopyralid triisopropanolamine salt commercial product ofDow AgroSciences, LLC.

Example 4

To make each of the herbicide formulations R through T shown in Table 7,a sample jar was first charged with 294 mL of deionized water, followedby 6 mL of the commercial herbicide formulation (either DMA6 SEQ,Clarity*, or Accord XRT II**) to make a 2% v/v dilution of theformulation. The sample was then shaken until homogeneous. To each ofthese solutions Veg-Ester GY-350 (Lubrizol, Inc.) was then added in anamount equal to 0.1% w/w of the diluted herbicide formulation. Thesample was once again shaken until homogeneous. The solutions were thensprayed following the same procedure and settings as described inExample 1, with the spray nozzle 12 inches (30.48 cm) from particlesizer measurement zone. The results are shown in Table 5. As can be seenfrom these results, the present invention does effectively reduce thedriftable fine droplets by altering the drop size distribution profilewithout significantly increasing the large droplets, thus having minimaleffect on spray coverage and quality.

TABLE 7 Spray Performance of Example 4 Compositions. Spray VMD, Percent< Percent < Solution Spray Composition μm 100 μm 175 μm Clarity 2%159.21 22.55 55.8 Accord XRT II 142.49 27.73 63.1 2% DMA6 SEQ 163.1521.79 54.2 2% R 2% Clarity 2% + 192.48 16.39 44.2 GY-350 0.1% S 2%Accord XRT II 2% + 160.58 21.52 55.4 GY-350 0.1% T 2% DMA6 SEQ 2% +175.55 20.21 49.7 GY-350 0.1% *Clarity, a 4 lb (1.81 kg) ae/gal dicambadiglycolamine salt commercial product of BASF corp. **Accord XRT II, a 4lb (1.81 kg) ae/gal glyphosate dimethylamine salt commercial product ofDow AgroSciences, LLC.

Example 5

1.40 ml of an aqueous solution of Dicamba dimethylammonium salt (DicambaDMA, 46.9% w/w a.e., 560.92 g a.e./L) and 0.649 g of Priolube 3952 wereadded to 324 ml of deionized water and hand shaken to yield a solutioncontaining 0.43% v/v of Dicamba DMA and 0.2% w/w of Priolube 3952. In asimilar manner, 1.45 ml of the Dicamba dimethylammonium salt solutionand 0.70 g of Agnique SBO-10 were added to 335 ml of deionized water toyield a solution containing 0.43% v/v of Dicamba DMA and 0.2% w/w ofAgnique SBO-10. As a control, 1.45 ml of the Dicamba DMA concentrate wasadded to 336 ml of deionized water to yield a 0.43% v/v solution.Finally, a 0.43% v/v solution of Clarity was prepared for comparison.The resulting solutions were sprayed and their droplet sizedistributions measured as described in Example 1, with the spray nozzle12 inches (30.48 cm) from particle sizer measurement zone. The resultsare summarized in Table 8. As can be seen from these results, thepresent invention does effectively reduce the driftable fine droplets byaltering the drop size distribution profile without significantlyincreasing the large droplets, thus having minimal effect on spraycoverage and quality.

TABLE 8 Spray Performance of Example 5 Compositions. Percent < Percent <Spray Solution VMD, μm 100 μm 175 μm 0.43% Dicamba DMA 159 22.4 55.40.43% Dicamba DMA + 260 6.2 23.1 0.2% Priolube 3952 0.43% Dicamba DMA +280 4.9 17.7 0.2% Agnique SBO-10 0.43% Clarity 161 21.5 55.1

Example 6

To 359.07 g of deionized water was added in order: 2.75 g of 2,4-Ddimethylethanolammonium salt solution (53.6% a.e.), 0.15 g of AgniqueSBO-10, 0.38 g of propylene glycol, and 3.52 g glyphosatedimethylammonium salt solution (42.2% a.e.). As a control, a secondsample was prepared as just described, except the Agnique SBO-10 wasreplaced with 0.15 g of additional deionized water. The resultingsolutions were briefly hand-shaken and then analyzed for their spraydroplet distributions as described in Example 1, with the spray nozzle12 inches (30.48 cm) from particle sizer measurement zone. The resultsare shown in Table 9.

TABLE 9 Spray Performance of Example 6 Compositions. VMD, Spray Solutionμm Percent < 100 μm Percent < 175 μm 0.40% 2,4-D a.e., 0.41% 159 22.456.1% Glyphosate a.e. 0.40% 2,4-D a.e., 0.41% 269 6.2 22.2% Glyphosatea.e. 0.04% + SBO-10

1. A method to reduce spray drift during the application of a pesticidewhich comprises incorporating into the pesticidal spray from about 0.01to about 5 percent vol/vol of a self-emulsifiable ester or mixturethereof.
 2. The method of claim 1 in which the pesticide is anherbicide.
 3. The method of claim 2 in which the herbicide is 2,4-D,glyphosate, triclopyr, aminopyralid, dicamba or mixtures thereof.
 4. Themethod of claim 1 in which the pesticide is an insecticide.
 5. Themethod of claim 1 in which the pesticide is a fungicide.
 6. The methodof claim 1 in which the self-emulsifiable ester is (1) trimer acid basedself-emulsifiable esters produced by the polymerization of oleic andlinoleic acids having a C₅₄ lipophilic backbone and an ester portion ofthe molecule containing both nonionic and anionic surfactantfunctionality; (2) esters prepared by esterification of ethoxylatedtrimethylolpropane by fatty acids and dicarboxylic acid anhydrides; (3)esters derived from high molecular weight dibasic acids, polyoxyalkyleneglycols and monofunctional aliphatic alcohols; (4) self emulsifyingester compounds prepared by reacting an ethoxylated trimethylol propanewith a carboxylic acid or a reactive derivative thereof; (5) succinatetriglyceride oil derived from maleating triglyceride oil from a plant orland animal; (6) ethoxylated fatty acid esters; (7) alkoxylate estersprepared by reacting an alcohol with ethylene oxide and propylene oxideand/or butylene oxide and capping the resulting alkoxylate with analkanoic or aromatic acid; and (8) alkoxylated triglycerides.
 7. Apremix formulation which comprises from about 1 to about 90 weightpercent of a pesticide and from about 0.05 to about 30 weight percent ofa self-emulsifiable ester.
 8. The premix formulation of claim 6 whichcomprises from about 20 to about 60 weight percent of a pesticide andfrom about 1.0 to about 10 weight percent of a self-emulsifiable ester.